Avoiding Routing Loops When Redistributing
Routing loops occur when a routing protocol redistributes routes into another protocol and then receives the same routes back—a process called route feedback. Because the metric is reset through redistribution, the routing protocol could see the redistributed path as more attractive. The potential for confusion is enormous, as shown in Figure 11-3; routes distributed from OSPF to EIGRP are distributed back to EIGRP at two redistribution points, causing the routing tables of..
The operation of RSVP is shown in Figure 14-12. Because the routed path from sender to receiver may be asymmetric, such as when the path for traffic from Host A to Host B is via R1, R2, R3, and the return path is via R3, R1, senders must prime the routers to expect reservation requests for a particular flow. This is accomplished by using path messages from the sender to the first hop router toward the receiver. The first hop router inserts its own address as the..
Network Deployment Considerations for RSVP-TE Graceful Restart
By now it should be clear that the support of the RSVP-TE GR mechanism requires that the restarting LSR be capable of preserving its MPLS forwarding state across its restart, the restarting LSR must inform neighbors about its GR capability before the restart, and the neighbors must also help the restarting LSR recovery procedure by retaining their RSVP-TE control plane/MPLS forwarding state across the restart and resynchronizing RSVP-TE state during the recovery period. Becau..
Protecting Management Plane Access
Other than the previously mentioned requirement for physical security, network security can be used to limit access to a device’s management plane over a network connection. For example, ACLs can be created to permit only specific protocols (such as SSH as opposed to Telnet and HTTPS as opposed to HTTP) coming from specific sources (for example, the IP addresses of administrators) to access a device’s management plane. Once a connection is made with the device to be manag..
Disabling EIGRP on an Interface
You can prevent an interface from participating in EIGRP by simply designating it as passive: Router1#configure terminal Enter configuration commands, one per line. End with CNTL/Z.Router1(config)#router eigrp 55Router1(config-router)#passive-interface Serial0/1Router1(config-router)#exitRouter1(config)#endRouter1# The passive-interface command in EIGRP prevents directly connected routers from establishing an EIGRP neighbor relationship. Since they can't become neighbor..
